About
WebAIM Contrast Checker is a free, browser-based tool developed by WebAIM (Web Accessibility In Mind), a non-profit organization at Utah State University. It calculates the contrast ratio between a foreground (text) color and a background color to help users determine whether their color combinations meet WCAG (Web Content Accessibility Guidelines) 2.x accessibility standards. Users can input hex color codes or use the built-in color pickers, and the tool instantly returns a pass/fail result for WCAG AA and AAA conformance levels. The tool evaluates contrast separately for normal text and large text, reflecting the different WCAG thresholds (4.5:1 for normal text at AA level, 3:1 for large text at AA level, and 7:1 / 4.5:1 at the stricter AAA level). It also includes a lightness slider to help users quickly adjust colors toward a passing ratio, and a companion link contrast checker that verifies hyperlink text is sufficiently distinct from surrounding body text and the page background. WebAIM Contrast Checker requires no registration or installation and is entirely free to use. It is widely used by web designers, front-end developers, accessibility auditors, and QA testers to validate color choices before publishing websites, applications, or digital content.
Key Features
- Real-Time Contrast Ratio Calculation: Instantly computes the contrast ratio between any two colors using the WCAG luminance formula as soon as hex values or color picker selections are updated.
- WCAG AA & AAA Compliance Reporting: Displays separate pass/fail results for WCAG 2.x Level AA (4.5:1 normal text, 3:1 large text) and Level AAA (7:1 normal text, 4.5:1 large text) standards.
- Interactive Color Pickers & Lightness Sliders: Built-in graphical color pickers and lightness sliders let users visually adjust colors until a passing contrast ratio is achieved.
- Normal vs. Large Text Distinction: Separately evaluates whether the chosen colors meet accessibility thresholds for both standard body text and large text (18pt+ or 14pt+ bold).
- Link Contrast Sub-Checker: A companion tool evaluates whether hyperlink color is sufficiently distinguishable from both the surrounding body text and the page background, addressing a distinct WCAG requirement.
Pros
- Completely Free with No Signup: The tool is provided as a public service by a non-profit and requires no account creation, installation, or payment.
- Instant, Standards-Based Results: Results update in real time and map directly to WCAG 2.x success criteria, making it straightforward to validate compliance.
- Covers Multiple Conformance Levels: Simultaneously reports AA and AAA results for both normal and large text, giving a complete picture in a single check.
- No Installation Required: Runs entirely in the browser, making it accessible on any device or OS without setup.
Cons
- Limited to Flat Color Contrast: The tool only evaluates solid foreground/background color pairs and cannot analyze gradients, images, or complex layered designs.
- No Batch or Bulk Checking: Colors must be entered and checked one pair at a time; there is no way to audit an entire stylesheet or design file in a single session.
- No API or Integration Support: The checker is a standalone web page with no API, meaning it cannot be embedded into automated testing pipelines or design tool workflows.
